I think what D. Allen may have been referring to when he talked about priorities was, for many people, the world just moves too fast. I was a rabid Franklin/FC user and Daytimer before GTD. I used priority codes all the time back then, although I don't remember sticking too them all that well.
But hey, I think it's great that you've customized your system in such a way that it works well for you! Personally, I got tired of sifting through all my contexts lists all day long and started making a daily "punch list" a couple of years ago. First thing in the morning, I go through all of my lists and pull out what I'd really like to get done that day and put them on a single list. I don't prioritize beyond that, but that is a means of prioritizing in itself, is it not?
Good discussion. It's great to see people who take the framework of GTD and make it work in their OWN life without having to argue about it with everyone else.